i48 HISTORY OF PERSIA CHAP. This prince was under great obligations to Yissugay, who had protected him when a refugee and had aided him to expel a usurping uncle and to regain the chieftainship. Consequently, when many years later he was again a refugee, having been driven out by his brother, who had the support of the Naiman—also a Christian tribe—he bethought himself of Temuchin, and was welcomed by the young chieftain. In A.D. 1194 we read that Temuchin led a contingent against the Buyr-Nurs under the Kin emperor, who commanded in person, and covered himself with glory in fighting and crushing the family foes. For some years after this campaign Temuchin fought with the tribes on every side and gradually organized his power. In A.D. 1202 he engaged in a trial of strength with his former ally Toghril, who at first defeated him ; but in A.D. 1203 he crushed the Keraits, who were thenceforth his subjects. Some time after this important success Tai Yang Khan, King of the Naimans, attempted to win over Ala Kush-Tekin, chief of the Onguts or White Tartars, with the design of, uniting in an attack on Temuchin before he became too powerful. But the Ongut chief in- formed the intended victim of the plot and he promptly attacked the Naimans, whom he crushed. Their king was killed, but his son, Guchluk, escaped and fled west- wards. Among the prisoners taken by Temuchin was Tatatungo, the Uighur Chancellor of Tai Yang, whom the conqueror took into his service. Tradition attributes the rudiments of civilization acquired by the Mongols to this remarkable man, who taught the sons of Chengiz the Uighur tongue and the art of writing, and who main- tained his influence under Ogotay, the son and successor of Chengiz. In A.D. 1206, so powerful had Temuchin become, that he was -in a position to assemble a Kuriltay, or " Diet of the Nobles," and at this historical assemblage he assumed the title of Chengiz Khan,1 or " The Perfect Warrior." The Downfall of the Kara Khitai Dynasty.—Guchluk, 1 This name varies in spelling from the Cambynskan, of Chaucer to the Zingis of Gibbon.